1. Field of the Invention
The present invention relates to surveillance cameras, and more particularly, to a surveillance camera with an adjustment mechanism for adjusting distance and focal length of a photographic lens in the surveillance camera.
2. Description of the Prior Art
Please refer to FIG. 8, which is a diagram of a surveillance camera according to the prior art. The surveillance camera comprises a housing 40. The front end of the housing 40 has a front opening 41, and the rear end of the housing 40 has a rear opening 42. A seal 43 is installed at the rear opening 42, a lens cover 44 is installed at the front opening 41, and a photographic lens 45 is installed in the housing 40 behind the lens cover 44.
The surveillance camera can be fixed at an appropriate position, and the photographic lens 45 can be adjusted to an optimum distance and focal length.
However, the surveillance camera is typically installed in a location relatively high above the ground. Thus, when the distance and focal length of the photographic lens 45 require adjustment, the lens cover 44 is first removed, after which a worker can attempt to refocus the photographic lens 45 by reaching through the front opening 41 into the housing 40 to adjust the distance and focal length of the lens by turning appropriate adjustment rings of the lens.
The photographic lens 45 and the housing 40 are only separated by a marginal gap. Therefore, it is very tedious and difficult for the worker to adjust the distance and focal length of the photographic lens 45, and when the distance and focal length of the photographic lens 45 need to be adjusted finely, the difficulty increases. Thus, it is difficult to adjust the distance and focal length of the photographic lens of the surveillance camera of the prior art, and fine adjustment is very difficult.